1. Objective(s): This proposal aims to profile abnormal glycosylation in prostate tumors of veterans, to determine if engineered chimeric antigen receptor (CAR) T cells targeting abnormally glycosylated proteins will demonstrate efficacy against bone-metastatic prostate cancer, and to evaluate mechanisms to improve T cell trafficking to tumor sites and enhance resistance to immunosuppression. 2. Research Design: De-identified veteran prostate cancers will be assembled into tumor tissue microarrays and profiled for abnormally glycosylated proteins through immunohistochemical and histopathological techniques, evaluated for spatial N-glycosylated epitopes through MALDI-TOF imaging, and characterized for O-glycosylated through cellular O- glycome reporter and amplification. An animal model of bone-metastatic prostate cancer will be developed through engraftment of a human osteoblast scaffold to support the bone-enrichment of implanted prostate cancer cell lines in NOD-SCID IL2R null (NSG) immunodeficient mice. ? Xenograft animals will be treated with a single intravenous dose of human CAR T cells (n=10 per treatment group) to measure the efficacy and potential treatment limitations of adoptive immunotherapy for bone metastases. Lastly, genetic engineering approaches will be evaluated to improve T cell bone homing and increase resistance to immunosuppression, including ectopic chemokine receptor expression and gene-disruption of immune checkpoint molecules. 3. Findings: Preliminary results demonstrate strong expression of Tn-MUC1 in bone- metastatic prostate cancer. 4. Clinical Relationships: CAR T cells have been explored in the clinic for over 6 years, have demonstrated remarkable success for hematopoietic malignancies, but have lacked sufficient clinical success in solid tumors. Nearly 10,000 veterans are diagnosed with prostate cancer per year and bone-metastatic prostate cancer remains a significant treatment challenge. Successful findings from this study could develop new treatment options for veterans with prostate cancer as well as improve CAR T cell adoptive immunotherapy for solid tumors.